This educational application supplements, but does not replace, the official AASHTO LRFD Bridge Design Specifications, applicable state DOT manuals, project specifications, and professional engineering judgment.
Independent Practice
Randomized problem sets, immediate feedback
Every problem regenerates its numeric inputs from realistic AASHTO ranges. Grade each step against a tolerance, retry with new numbers, and export attempts to your progress transcript. 219 problems across 18 chapters.
Ch 1
Bridge functions, classifications, systems, and the design–build–inspect lifecycle. Overview of AASHTO LRFD, engineering ethics, and how bridges fit into the transportation network.
Ch 2
Evolution from ASD to LFD to LRFD. Reliability, load and resistance factors, ductility, redundancy, operational importance, and the four AASHTO limit states.
Ch 3
Permanent and transient loads, HL-93 live loading, dynamic load allowance, multiple-presence factors, braking and centrifugal effects, and Strength / Service / Fatigue / Extreme-Event combinations. Includes a full three-span Mid-Atlantic bridge worked example.
Ch 4
Load paths, influence lines and surfaces, live-load distribution factors, approximate methods vs. refined analysis, grillage and finite-element models, and validation.
Ch 5
AASHTO equivalent-strip method, empirical design, minimum reinforcement and cover, distribution steel, crack control, and Extreme Event II overhang design. Complete concrete-deck worked example plus a full steel orthotropic-deck example with the three stress systems (local, panel, global) and rib-to-deck weld fatigue check.
Ch 6
Solid slab, T-beam, and RC box-girder bridge design. Effective flange width, Whitney stress block flexural design, AASHTO simplified sectional shear method, torsion in boxes, and detailing. Includes a full T-beam worked example (flexure + shear + fatigue + deflection) and a solid slab bridge example, plus a two-span continuous T-beam design challenge.
Ch 10
Bearing families (elastomeric, pot, disc, spherical), Method-A design of a steel-reinforced elastomeric pad, joint movement from thermal + shrinkage + creep, and joint-family selection (strip-seal, modular, finger). Full worked examples for an elastomeric bearing pad and a strip-seal joint plus a curved-bridge design challenge.
Ch 7
Pre-tensioned and post-tensioned girder design. Losses, transfer and service stresses, flexural and shear strength (§5.7, §5.8, §5.9), harped and debonded strand layouts, end-zone anchorage-zone design, deflection and camber. Includes a full AASHTO Type-VI girder worked example, a spliced post-tensioned example, and a mini design challenge.
Ch 8
Rolled and welded plate composite steel girders. Section classification, plastic and yield-moment resistance, LTB, shear with tension-field action, shear stud design, and Category-C fatigue. Includes a full 2×140-ft continuous composite plate-girder worked example and a curved-girder mini design challenge.
Ch 9
Pier and bent classification, load path from superstructure to foundation, slenderness and moment magnification, biaxial P–M interaction for RC columns, bent-cap flexure and shear, and seismic detailing. Includes a full multi-column bent worked example, a hammerhead pier example, and a bent design challenge.
Ch 11
High-strength bolted and welded connections per AASHTO §6.13. Bolted field splices (75 %-of-yield rule, flange direct force, web elastic-vector), cross-frame families and spacing, top-flange lateral bracing during construction, and gusset-plate design. Worked examples for a bolted flange splice and a cross-frame diagonal plus a 3-span composite design challenge.
Ch 12
Abutment families (stub, seat, cantilever, MSE), Rankine active earth pressure, live-load surcharge, and stability checks for sliding, overturning, and bearing. Cantilever stem/toe/heel design, wingwalls, approach slabs, and integral abutment thermal demand. Two worked examples plus a river-crossing design challenge.
Ch 13
Spread footings, driven piles, drilled shafts, and micropiles per AASHTO §10. Meyerhof bearing capacity, α/β pile methods, O'Neill–Reese rock socket, p-y lateral analysis, group efficiency, and downdrag. Full worked examples for a spread footing and a driven pile group plus a river-crossing drilled-shaft design challenge.
Ch 15
AASHTO seismic hazard, design response spectrum, single-mode SDOF analysis, response modification factor R, plastic-hinge detailing and spiral confinement, capacity-design hierarchy, and seismic isolation. Two worked examples (design base shear and plastic-hinge confinement) plus a four-span SDC-D design challenge.
Ch 16
AASHTO §3.8 wind pressure and aeroelastic screening (buffeting, vortex shedding, flutter), §3.14 vessel-impact Method II, §3.6.5 vehicular collision, §3.9 ice loads, Extreme Event I/II combinations, and multi-hazard resilience framing. Two worked examples (wind pressure and barge impact) plus a cable-stayed multi-hazard design challenge.
Ch 18
Construction engineering for bridges — erection schemes (span-by-span, balanced cantilever, incremental launching, cable-stayed cantilever), formwork and falsework, camber, temporary works, construction loads and combinations, and rigging/lifting. Two worked examples (falsework check + segmental balanced-cantilever unbalanced moment) and a full girder-erection design challenge.
Ch 19
NBIS 23 CFR 650 inspection program (routine, in-depth, fracture-critical, underwater, damage, special), FHWA NBI condition ratings 0–9, common deterioration mechanisms and NDT toolbox, and AASHTO MBE §6A Load and Resistance Factor Rating — Design (Inventory + Operating), Legal, and Permit — with a worked example on a deteriorated composite plate girder and a full 3-span river-crossing evaluation design challenge.
Ch 20
FHWA intervention hierarchy (preservation · rehabilitation · replacement), deck treatments (crack seal, thin polymer, LMC, HMA + membrane), superstructure retrofits (FRP confinement per ACI 440.2R, external post-tensioning, drill-stop + bolted splice for fatigue), substructure jacketing, and life-cycle cost analysis at real discount rates. Full external-PT worked example, a 3-span overpass rehab design challenge, and a PE-format graded quiz.
How immediate feedback works
Each step in every problem is graded against a symbolic expected value with a default tolerance of 2%. Hit Check to see per-step ✓ / ✗, then reveal the worked solution or hit New numbers to re-randomize inputs and try again.